Although supplemental oxygen during surgery and for the first two-to-six hours after surgery halves the risk of surgical wound infection, it remains unknown whether prolonged supplemental postoperative oxygen significantly augments the benefits of intraoperative oxygen. There is some evidence suggesting that prolonged postoperative oxygen administration may be helpful. For example, experimental infections in guinea pigs are reduced by administration of supplemental oxygen for 45 h. In contrast, restricting oxygen for only 45 minutes after contamination reduces tensile wound strength in rabbits no more than restricting oxygen for 5 full days. No study in humans has evaluated the effects of supplemental postoperative oxygen on surgical wound infection or associated complications.